A man and a woman live with their three adult children in a secluded, fenced-in compound, completely isolated from the outside world. The parents have enforced a bizarre regime of control and misinformation, teaching the children erroneous definitions of common words, instilling irrational fears, and holding elaborate, deceptive stages of events to keep them obedient. The children believe they will be ready to leave the compound only when they lose a "dogtooth," something highly unlikely to happen as per their father's explanation. They have never ventured beyond the tall walls and blindly trust in the narrative fed to them by their parents.

Their father occasionally brings Christina, a security guard from his workplace, who is paid to satisfy the sexual urges of the eldest son. However, Christina inadvertently disrupts the controlled environment by introducing alien ideas and influences. Her actions sow seeds of curiosity and rebellion in the eldest daughter, who begins to yearn for new experiences and an understanding of the world outside the compound. The family’s carefully constructed facade starts to crack, exposing the deep dysfunction and increasing strain on maintaining such a controlled existence. As the eldest daughter becomes more influenced by Christina’s inadvertent provocations, the foundation of the family’s isolationist regime faces unprecedented challenges.